• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.859-865
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• 2003

Surfactin is a mixture of cyclic lipopeptides built from variants of a heptapeptide and a ${\beta}-hydroxy$ fatty acid produced by several strains of Bacillus sp. Surfactin isoforms produced by endophytic Bacillus sp. CY22 from a balloon flower were isolated and characterized. It was found that the purified surfactin had three isoforms with protonated masses of m/z 1,008, 1,022, and 1,036, and different structures in combination with Na, K, Ca ions using MALDI-TOF MS, ESI-MS/MS, and ICP MS, respectively. In the MS/MS analysis, the isolated surfactin had the identical amino acid sequence (LLVDLL) and hydroxy fatty acids (with 13 to 15 carbons in length), even though isolated from different Bacillus strains. The sfp22 gene, required for producing the surfactin, consisted of an open reading frame (ORF) of 675 bp encoding 224 amino acid residues with a signal peptide of 20 amino acids. The predicted amino acid sequence of sfp22 was very similar to that of Ipa-8.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.37-43
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• 2007

A gene encoding inulin fructotransferase (di-D-fructofuranose 1,2': 2,3' dianhydride [DFA III]-producing IFTase, EC 4.2.2.18) from Bacillus sp. snu-7 was cloned. This gene was composed of a single, 1,353-bp open reading frame encoding a protein composed of a 40-amino acid signal peptide and a 410-amino acid mature protein. The deduced amino acid sequence was 98% identical to Arthrobacter globiformis C11-1 IFTase (DFA III-producing). The enzyme was successfully expressed in E. coli as a functionally active, His-tagged protein, and it was purified in a single step using immobilized metal affinity chromatography. The purified enzyme showed much higher specific activity (1,276 units/mg protein) than other DFA III-producing IFTases. The recombinant and native enzymes were optimally active in very similar pH and temperature conditions. With a 103-min half-life at $60^{\circ}C$, the recombinant enzyme was as stable as the native enzyme. Acidic residues and cysteines potentially involved in the catalytic mechanism are proposed based on an alignment with other IFTases and a DFA IIIase.

• Journal of fish pathology
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• v.14 no.2
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• pp.59-64
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• 2001

A complementary DNA encoding metallothionein(MT), a heavy metal-responsive protein was cloned from a cartilaginous shark species. Scyliorhinus torazame. An expressed sequence tag(EST)from the shark liver, which showed high similarity with a MT gene, was isolated and its full-length sequence(390bp)was determined. The putative shark MT cDNA sequence contained an open reading frame consisting 68 amino acids and 182bp of 3-untranslated region including the poly (A+) signal. The deduced amino acid sequence was 41-54% identical to those of other animals including mammals and fish species. Tiger shark MT cDNA showed high conservation in the Cys regions. however, peculiarly contained not only additional five amino acids just prior to the conserved beta-domain but also a Ser residue at C terminal, which has not been seen in other MT sequences.

• Journal of Microbiology and Biotechnology
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• v.16 no.11
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• pp.1753-1759
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• 2006

Paenibacillus sp. HY-8 isolated from the digestive tracts of the longicorn beetle, Moechotypa diphysis, produced an extracellular endoxylanase with a molecular weight of 20 kDa estimated by SDS-PAGE. The xylanase was purified to near electrophoretic homogeneity from the culture supernatant after ammonium sulfate precipitation, gel filtration, and ionexchange chromatography. The purified xylanase exhibited the highest activities at pH 6.0 and $50^{\circ}C$. The $K_m\;and\;V_{max}$ values were 7.2 mg/ml and 16.3 U/mg, respectively, for birchwood xylan as the substrate. Nucleotide sequence of the PCR-cloned gene was determined to have the open reading frame encoding a polypeptide of 212 amino acids. The N-terminal amino acid sequence and the nucleotide sequence analyses predicted that the precursor xylanase contained a signal peptide composed of 28 amino acids and a catalytically active 19.9-kDa peptide fragment. The deduced amino acid sequence shared extensive similarity with those of the glycoside hydrolase family 11 of xylanases from other bacteria. The predicted amino acid sequence contained two glutamate residues, previously identified as essential and conserved for active sites in other xylanases of the glycoside hydrolase family 11.

• Journal of Microbiology and Biotechnology
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• v.19 no.3
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• pp.257-264
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• 2009

A $\beta$-agarase gene, agaB34, was functionally cloned from the genomic DNA of a marine bacterium, Agarivorans albus YKW-34. The open reading frame of agaB34 consisted of 1,362 bp encoding 453 amino acids. The deduced amino acid sequence, consisting of a typical N-terminal signal peptide followed by a catalytic domain of glycoside hydrolase family 16 (GH-16) and a carbohydrate-binding module (CBM), showed 37-86% identity to those of agarases belonging to family GH-16. The recombinant enzyme (rAgaB34) with a molecular mass of 49 kDa was produced extracellularly using Escherichia coli $DH5{\alpha}$ as a host. The purified rAgaB34 was a $\beta$-agarase yielding neoagarotetraose (NA4) as the main product. It acted on neoagarohexaose to produce NA4 and neoagarobiose, but it could not further degrade NA4. The maximal activity of rAgaB34 was observed at $30^{\circ}C$ and pH 7.0. It was stable over pH 5.0-9.0 and at temperatures up to $50^{\circ}C$. Its specific activity and $k_{cat}/K_m$ value for agarose were 242 U/mg and $1.7{\times}10^6/sM$, respectively. The activity of rAgaB34 was not affected by metal ions commonly existing in seawater. It was resistant to chelating reagents (EDTA, EGTA), reducing reagents (DTT, $\beta$-mercaptoethanol), and denaturing reagents (SDS and urea). The E. coli cell harboring the pUC18-derived agarase expression vector was able to efficiently excrete agarase into the culture medium. Hence, this expression system might be used to express secretory proteins.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.95-100
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• 2004

This paper represents the development of a CLS(Control Loading System) for a target a airplane (KT-1) with mechanical linkage reversible flight control system. The system is composed of mechanical frame, controller, sensing part to measure the force from the stick, driving system generating the reaction forces. The DS1103 DSP(Digital Signal Processor) of the dSpace Corp. was used as the controller. The control algorithm of the CLS and the operational environment including monitoring software and evaluation tools are described. The evaluation of the system was conducted according to the requirement specification. The results of the test were analyzed by comparing with the actual data of the target airplane.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.547-552
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• 2003

In this thesis, interference phenomena of bluetooth networks requiring Security were minimized; strengthened security of piconet by assigning an identical PIN code to bluetooth devices, which was establishing a specific piconet during authentication stage. To establish a bluetooth piconet system. an unique ID was assigned to each bluetooth device, communication algorithms having different data formats between devices was designed, and an embedded hardware module using ARM processor and uCOS-II RTOS was implemented. About 30% of CPU efficiency in the module was increased by modifying functions including block parameters to work as nonblocking; by the increased efficiency of total piconet, the module could be used as an access point. The module could transmit maximum 10 frames of image and also audio signal by switching the packet effectively according to channel condition. By above-mentioned process, video, audio, and data could be well transmitted by the bluetooth managing program and the possibility of a commercial remote control system using bluetooth technology was suggested.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.157-167
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• 2000

A thermostable chitosanase gene from the isolated strain, Bacillus sp. CK4, was cloned, and its complete DNA sequence was determined. The thermostable chitosanase gene was composed of an 822-bp open reading frame which encodes a protein of 242 amino acids and a signal peptide corresponding to a 30 kDa enzyme in size. The deduced amino acid sequence of the chitosanase from Bacillus sp. CK4 exhibits 76.6%, 15.3%, and 14.2% similarities to those from Bacillus subtilis, Bacillus ehemensis, and Bacillus circulans, respectively. C-terminal homology analysis shows that Bacillus sp. CK4 belongs to the Cluster III group with Bacillus subtilis. The size of the gene was similar to that of a mesophile, Bacillus subtilis showing a higher preference for codons ending in G or C. The functional importance of a conserved region in a novel chitosanase from Bacillus sp. CK4 was investigated. Each of the three carboxylic amino acid residues were changed to E50D/Q, E62D/Q, and D66N/E by site-directed mutagenesis. The D66N/E mutants enzymes had remarkably decreased kinetic parameters such as $V_{max}$ and k$\sub$cat/, indicating that the Asp-66 residue was essential for catalysis. The thermostable chitosanase contains three cysteine residues at position 49, 72, and 211. Titration of the Cys residues with DTNB showed that none of them were involved in disulfide bond. The C49S and C72S mutant enzymes were as stable to thermal inactivation and denaturating agents as the wild-type enzyme. However the half-life of the C211S mutant enzyme was less than 60 min at 80$^{\circ}C$, while that of the wild type enzyme was about 90 min. Moreover, the residual activity of C211S was substantially decreased by 8 M urea, and fully lost catalytic activity by 40% ethanol. These results show that the substitution of Cys with Ser at position 211 seems to affect the conformational stability of the chitosanase.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.6-10
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• 2015

RF energy harvesting technology is a promising technology for generating the electrical power from ambient RF signal to operate low-power consumption devices(eg. sensor) in wireless communication networks. This paper, motivated by this and building upon existing CR(Cognitive Radio) network model, proposes a optimal control policy for RF energy harvesting CR networks model where secondary users that have low power consumption harvest ambient RF energy from transmission by nearby active primary users, while periodically sensing and opportunistically accessing the licensed spectrum to the primary user's network. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.

• Journal of Korea Multimedia Society
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• v.10 no.8
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• pp.1039-1051
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• 2007

In this paper, a new lip synchronization control method is proposed to achieve very low delay in the video communication. The lip control is so much vital in video communication as delay reduction. In a general way, to control the lip synchronization, both the playtime and capture time calculated from RTP time stamp are used. RTP timestamp is created by stream sender and sent to the receiver along the stream. It is extracted from the received packet by stream receiver to calculate playtime and capture time. In this paper, we propose the method of searching most adjacent corresponding frame of the audio signal, which is assumed to be played with uniform speed. Encoding buffer of stream sender is removed to reduce the buffering delay. Besides, decoder buffer of receiver, which is used to correct the cracked packet, is resulted to process only 3 frames. These mechanisms enable us to achieve ultra low delay less than 100 ms, which is essential to video communication. Through simulations, the proposed method shows below the 100 ms delay and controlled the lip synchronization between audio and video.